Question

I am trying to implement a function that will insert a new entry in a database if a field with same name (as the one given) doesn’t already exist. In particular I want to restrict duplicate usernames in a table.

The only way I could think was to run a select query and then if that doesn’t return anything run the insert query. For some reason though I cant get it to work…

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My db select Function

function getAllUsers($user)
{
    $stmt = $this->db->stmt_init();
    $stmt->prepare('SELECT username from users where username=? ');
    $stmt->bind_param("s", $user);
    $stmt->bind_result($username);
    $stmt->execute();
    $results = array();
    while($stmt->fetch())
    {
        $results[] = array('username' => $username);
    }        
    $stmt->close();        
    return $results;
}

---

My php code (this is in a different page)

foreach ($GLOBALS['db']->getAllUsers($_POST['username']) as $i)
{
    $results =  "".$i['username']."";       
    break;
}    
if(strcmp($results, "")==0)
{
    if($GLOBALS['db']->addUser($_POST['username'],$_POST['password']))
    {
            session_destroy();                
            echo "registerSucces";
    }
    else
    {
            session_destroy();
            echo "registerError";
    }
}
else
{
        echo "userNameExists";
}

Can you see whats wrong with this???

Thanks

Mike

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Still cant find how to make the above code work but just in case someone needs this: A temporary simple solution is not to compare strings at all and instead have a counter in the foreach loop and then check that upon a desired number(0 in my case)…

Answer 1

SQLite supports the UNIQUE constraint. Simply declare a UNIQUE index on the column and check whether an INSERT fails.